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I'm Verna,
Your Curly-Haired Friend.

Curly hair is like a box of chocolates, you never know what you're going to get. It could be super-defined one day and a frizzy concoction the next day – and it's never exactly the same from one head to another. Our mission is to equip you with the necessary tools for restoring and maintaining healthy locks and celebrating the hair you were born with! 

The Mystery of Protein Sensitive Hair: Solved

January 31, 2020


Verna Meachum

Find out if protein sensitive hair is a thing.

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Curl care

With extensive experience in the beauty industry, I specialize in writing for curly hair care brands, websites, and magazines.

Not only do I have curly hair, but my children, friends, family members, and even friends who are professional curly hairstylists, each with their unique curly textures.

 You get the point :) 

I also partner with a friend who holds a Ph.D. in chemistry and works as an R&D Chemist, ensuring our content is scientifically accurate and help us navigate through the misinformation around curly hair care. 

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Last Updated on April 9, 2023 by Verna Meachum

I know it can seem like we’re always hearing about a new potential problem in the curly hair community, but that’s only because we’re a passionate bunch who love to talk about our hair! The latest issue on everyone’s mind? Protein sensitive hair.

The definition of protein sensitive hair is still up for debate, but it generally refers to hair that doesn’t respond well to products containing proteins. This can manifest in a few different ways, from frizzy hair to stiff hair.

However, protein sensitive hair is not actually a permanent condition and there are plenty of ways to deal with it.

Do I Have Protein Sensitive Hair?

If you’re not sure whether or not you have protein sensitive hair, there are a few symptoms that may indicate you do:

  • Dull hair
  • Dry hair
  • Frizzy hair
  • If you find that your hair is hard, rough, and stiff, even though you’re using good quality hair care products.
  • You’ve been using emollients, and/or natural oils/butters, but it’s no use, your hair is still hard, stiff, and may break upon bending.

How To Test Your Hair For Protein Sensitivity?

  • Take a few fibers of your hair (always choose from the back underneath section for a test).
  • Wet the hairs with a few drops of water and wipe away any extra moisture with whatever material you prefer.
  • Apply a small amount of protein product from the market.
  • Leave it on your hair for 5 minutes.
  • Rinse off and dry.
  • Touch the hairs. If they feel hard, stiff, or break off, your hair is probably protein sensitive.

Why is My Hair Protein Sensitive?

Hair is a protein by nature, and this protein is called keratin. The structure of keratin is helical, where two strands of protein chains are bonded together through various bonds.

To understand the mechanical stiffness of hair as a result of protein application, we need to understand the chemical bonding inside keratin.

Salt Bonds

This bonding involves oppositely charged chemical groups of two peptides (protein) chains. These bonds can be broken by pH changes in the hair, in both the acid or alkaline direction. Readjusting the hair’s pH will reform and stabilize these bonds.

Disulfide Bonds

This is the most important chemical bond present in hair structure and is responsible for the mechanical strength of hair.

These bonds cannot be broken by water or heat manipulation. Only chemical agents can break these bonds, and once these bonds are broken, they cannot be reformed back again.

It is the main site of action for chemical treatments for permanent hair reshaping and styling.

For example:

  • Perming
  • Hair straightening
  • Relaxing

Under alkaline conditions, disulfide linkages are converted to lanthionine bonds resulting in a permanent chemical change, which is a process generally used in permanent hair straightening.

The more disulfide bonds that occur in the fiber, the curlier, and kinkier the hair (i.e. 4 type hair pattern).

The higher in porosity your hair is, the weaker and/or fewer disulfide bonds are.

The lower in porosity your hair is, the more and/or tighter the disulfide bonds are.

Hydrogen Bonding

These are the most flexible bonds that are easily broken in the presence of water.

When the hair is wet during washing or in the presence of a lot of humidity, water molecules enter and break apart these hydrogen bonds.

The good thing is that they are easily changed back. Hydrogen bonds allow the hair to change shape temporarily and produce a strong hold. (i.e., wet setting, roller sets). This explains why high humidity causes large frizz and hairstyling problems.

Protein treatments are designed to interact strongly with these chemical bonds.

Proteins may act or react with hair via two strategies. Small molecules of protein enter the hair via cracks/holes in the cuticles, and they are firmly bound within.

While large protein molecules form a coating, creating a strong film along the hair shaft.

From the above points, your protein sensitivity problems might be caused by one of the following two reasons.

You used the wrong protein for your hair type

Every person has a distinct type of hair fibers and texture.

Some of us have had our hair chemically altered in some way, whether it be by perms, relaxers, or oxidative coloring.

These chemical treatments leave hair highly porous with gaps/holes in the cuticle and cortex. If we were to use large protein molecules, they may not be able to penetrate and only get deposited at the hair’s surface, leaving inner empty spaces still empty.

In simple terms, you are using the wrong protein at the wrong time.

So, what do we need to do?

We need small protein molecules that can penetrate the hair and fill the gaps. Proteins that are too large may just deposit on the surface and make hair more stiff and hardened.

Protein overload or build up

Another cause of your protein sensitive hair problems may be due to using too much protein, resulting in the accumulation of protein molecules at the hair’s surface. This may also happen when using higher molecular synthetic polymers.

Hair becomes unmanageable, dull, and limp as a result of the build-up.

With repeated applications of proteins, this build up continues and eventually, your hair will harden.

How To Prevent And Resolve Protein Sensitive Hair

A sensitivity to protein might be indicated by an adverse reaction to it during or after application.

The problem is since there are so many ingredients in a product, how do you know which one is causing the problem?

It’s possible that it’s a mixture of ingredients that you’re sensitive to rather than the protein itself, but the only way to figure out what is causing the problem is through trial and error.

Everyone’s hair is unique and will react differently. But, what makes it more complicated is that not all proteins are the same.

So, before declaring yourself protein sensitive, think about the types of protein you apply to your hair, how often you apply them, and your hair’s current condition.

There are many types of proteins extracted from various sources.

For example:

  • Milk
  • Oats
  • Wheat
  • Rice
  • Quinoa
  • Soy
  • Keratin, etc.

These are all different in molecular weight, size, and chemical composition of amino acids.

The table below describes some of the protein for curly hair used in hair care products. It also tells us their amino acid profile (in percentage).

Amino AcidHuman
Wheat ProteinSoyaRiceOat CollagenMilkSilkQuinoa
Alanine4.502.704.505.906.409.304.50 29.80 2.17
Arginine9. 3.02
Aspartic acid9.003.1012.309.208.606.307.30 1.17 3.69
Cystine13.001.801.002.400.40 0.13
Glutamic acid18.1036.8020.1020.4024.309.6020.60 0.41 8.75
Glycine5.603.504.504.608.8024.603.20 46.00 3.00
Histidine13.002.202.603.402.200.902.80 2.17
Isolucine2.403.403.805.002.601.604.40 0.33 0.82
Lucine4.607.307.409.107.503.307.20 0.17 2.48
Lysine3.601.706.403.704.103.807.30 2.35
Methionine0.801.501.302.101.801.002.40 0.31
Phenylalanine2.305.404.805.904.302.303.00 5.70 1.54
Proline9.3012.005.304.403.9013.6012.30 1.82
Serine13.105.705.404.905.103.007.7011.45 1.66
Theronine9.102.904.103.703.402.005.10 1.12 5.71
Tryptophan1.201.50 1.03
Tyrosine0.800.903.602.000.900.303.30 1.66 1.20
Valine5.204.104.706.903.903.205.70 2.19 0.99
Table 1: Amino acid profile of various proteins. The data is an average of multiple data sets. 1-2

Proteins that contain high levels of glutamic and aspartic acids are better for hair conditioning, moisturizing, and hydration (for example, wheat and oat protein).

Human hair keratin is rich in sulfur-containing cystine, which provides hair strengthening and improves its tensile properties.

Things to Keep in Mind

Products that have protein listed among the first 5 – 6 ingredients have a higher concentration of proteins.

Even those of us who do a lot for our curls may sometimes feel we need to strengthen our hair and can overdo it with protein. It’s not so much that we have “protein sensitive hair,” it’s just that we need to cut back on the frequency.

So, in this situation, do not use protein products as frequently.

Keep in mind that applying three products could mean you’ve put ten or more protein ingredients on your strands. As a result, it’s critical to understand the ingredients, but the product combination and quantity are also significant.

Clarify your hair

Wash your hair with a clarifying shampoo, as it is important to remove protein and any polymeric build up.

However, it does not necessarily mean you need a sulfate shampoo, a good mild cleanser will do a great job. This cleansing should be followed by emollients and a moisturizing treatment to provide much-needed moisture to your hair.


Protein treatments are essential for our hair because they strengthen and repair the hair shaft and enhance the ability to absorb and maintain moisture.

Water molecules bind easily to a good protein structure within the hair shaft; hence, it’s imperative to maintain a protein/moisture balance. However, we need to know our hair and what it needs.

Applying every other protein product we find on the market is not the solution.

Excess of anything is not always a good thing, as an excess of proteins may actually leave your hair unhealthy.

Choose the right protein that best suits your hair. It’s all a matter of knowing and paying attention to what your hair needs.

Read labels carefully. I can’t emphasize this enough. Keep track of which items your hair responds to, whether positively or negatively. You are the most qualified person to determine what ingredients work best for you.

As I always, say, let your hair be your guide!

Further reading

1. Zviak, C., The Science of Hair Care. Taylor & Francis: 2005.
2. Robbins, C. R., Chemical and physical behavior of human hair. 4th ed.; Springer-Verlag: New York, 2002.
3. Corporation, A. P., Hair Care: From Physiology to Formulation. Allured Publishing Corporation: 2008.

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